Plural gaseous electric discharge device starting circuit using an unignited discharge device as ballast



Aug. 27. 1968 SHUNGO FURUI 3,399,327

PLURAL GASEOUS ELECTRIC DISCHARGE/DEVICE STARTING CIRCUIT USING ANUNIGNITED DISCHARGE DEVICE AS BALLAST Filed Feb. 24, 1967 5 5 INVENTORSHUNGO FURUI My n l e BY /M A ATTORNEY United States Patent 3,399,327PLURAL GASEOUS ELECTRIC DISCHARGE DE- VICE STARTING CIRCUIT USING ANUNIG- NITED DISCHARGE DEVICE AS BALLAST Shungo Furui, Yokohama, Japan,assignor of twenty-five percent to Yasuka Akamatsu, Sacramento, Calif.Filed Feb. 24, 1967, Ser. No. 618,421 Claims priority, applicationJapan, Mar. 3, 1966, 41/ 12,598 1 Claim. (Cl. 315-189) ABSTRACT OF THEDISCLOSURE This invention relates to a circuit for starting two or moregaseous discharge lamps which are connected in series to a voltagesource, comprising impedance means connected in parallel to one of saidlamps, and a glow switch having normally closed contacts connected inseries with said impedance means and in parallel with another of saidlamps, said glow switch initially short circuiting said other lampthereby to enable starting of said one lamp and subsequently upon firingof said glow switch removing said short circuit to cause said other lampto start.

This invention relates to starting circuits for gaseous discharge lampsystems, and more particularly to improvements in such circuits asdisclosed in a copending application for patent Ser. No. 621,737, filedMarch 6, 1967, by the present inventor and which is incorporated hereinby reference.

In the aforementioned application, a pair of gaseous discharge lamps,such as mercury vapor or fluorescent lamps, are connected in series to avoltage source. Across one of the lamps or devices is connected animpedance of relatively high value. Across the other device or lamp isconnected a starter switch means comprising a glow switch and a relayoperable by the glow switch in such a manner as to first short circuitthe other lamp, and subsequently remove the short circuit. Shortcircuiting of the other lamp causes the entire voltage to be applied tothe one lamp, thereby causing it to start. When the glow switch causesthe relay to remove the short circuit, the two lamps are connected inseries to the voltage source. Since the lamps exhibit negative impedancecharacteristics immediately upon lighting, once the one lamp is lit,most of the voltage will be placed on the other lamp when the shortcircuit is removed, thereby causing the other {lamp to start.

The glow switch of the copending application comprises a normally openswitch which may be closed by a glow discharge in the glow switch. Theimpedance connected across the one lamp is of suflicient value to enablethe glow switch to fire, but is insufficient to cause the lighting ofthe lamp. Also, the glow switch is connected to a relay which places theshort circuit and removes it at the appropriate times.

In the present invention, which has as its object the improvement of theinvention of the copending application, the foregoing glow switch andrelay are replaced by a single glow switch which comprises normallyclosed type switch contacts contained within an envelope filled withsuitable gas, such as argon or neon. The operation of the presentinvention is similar to the other invention, with the exception thatinstead of the glow switch being used to operate a relay which in turnprovides and removes the short circuiting of the other lamp, a singlenormally closed switch is used to initially place a short circuit acrossthe other lamp thereby causing it to start instantaneously.Simultaneously, the voltage is applied to the impedance means connectedto the glow Kit:

switch to cause it to fire. The glow discharge causes the bimetalliccontactor contained therein to open the normally closed contacts, andthus remove the short circuit. Thereafter the impedance will be ofsuflicient value to keep the glow switch tube fired and thus keep theswitch open. The lamps and glow switch are turned off by removal of thevoltage source.

Thus, one feature of this invention is the provision of a normallyclosed switch together with a suitable im pedance means such as toinitially place a short circuit across one lamp and to subsequentlyremove the short circuit thereby to enable the one lamp and another lampto be lit in sequence.

The foregoing and other objects and features of this invention willbecome evident upon consideration of the following detailed descriptionand drawing in which:

FIG. 1 depicts one illustrative embodiment of this invention as used forslim line fluorescent lamps; and

FIGS. 2 and 3 depict other embodiments of this invention as used forrapid start (FLR) type fluorescent lamps.

Referring to the drawings, FIGS. 1, 2 and 3 depict lamp systems similarto those disclosed in the aforementioned copending application, with theexception of glow switch 5 and capacitor 12. These systems have theirelements denoted with similar numerals and letters for convenientidentification.

In these figures, there are connected in series circuit discharge lampsor devices 3 and 4 (being slim line fluorescent lamps in FIG. 1 andrapid start (FLR) type fluorescent lamps in FIGS. 2 and 3), each havingtwo electrodes or heaters 3A, 3B and 4A, 4B (with ground static shields16 and 17 in FIGS. 2 and 3); transformer 1 having primary winding 1A,secondary winding 1B, and terminals 13, 14 and 15; and a shuntcombination of impedance or resistor 10 and capacitor 2, both being ofsuitable values. The transformer has connected to it via switch S, agenerator G of suitable type and capacity. Connected in shunt to thefirst lamp 3 is an impedance 9 of appropriate high value, such as a highresistance, a high capacitance or a high inductance.

As explained in the aforementioned application, the transformer 1 may beof such type that its no-load secondary voltage is relatively small anda leakage pass may be used. The windings 1C, 1D and 1B in FIGS. 2 and 3,are used to provide heating energy to the filaments of lamps 3 and 4.

Also common to the figures, but only in this invention, there isdepicted glow switch 5 which comprises fixed contactor 6 and electrode8, and a bimetallic movable contact 7. The contacts 7 and 8 are coatedwith barium oxide or other suitable material to provide suitableelectrodes for the firing of the tube 5. Connected to the terminals ofthe tube 5 are noise suppressor capacitors 11 and 12, and via leads toimpedance 9, lamp 4, capacitor-resistor combination 2-10, and lamps 3and 4, all in the manner depicted.

When a suitable voltage is applied between contacts 7 and 8, a gaseousdischarge is caused to occur in the tube 5. Heat produced from the glowcauses contact 7 to move to the right until the normally closedcondition is broken. The bias to cause the glow discharge in device 5 isprovided by impedance 9, which is of sufficient value to cause the glowdischarge in tube 5 and to also protect the system from excess currentin the event contact 7 should accidentally touch element 8.

The capacitor-impedance combination 2-10 is used to provide staticdischarge.

The operation of all the embodiments of FIGS. 1, 2 and 3 are similarexcept for minor differences due to different types of lamps used andthe different methods of heating thus required of such lamps. Whenswitch S secondary voltage 'is applied tothe series connected lamps 3and 4. The second lamp is initially short circuited by the normallyclosed contacts of glow switch 5. Thus, substantially all of the voltageis applied to lamp 3, which is thereby caused to start. Concurrently,voltage is applied via impedance 9 to the glow switch 5, causing it tofire. The glow discharge being of suflicient heat, causes bimetallicelement 7 to bend to the right and thus break its contact with contact6. The speed with which the bimetallic element 7 bends and breakscontacts is sufliciently delayed to enable lamp 3 to start. When thecontactbetween contacts 6 and 7 is broken, the short circuit across lamp4 is removed. Substantially all of the voltage is now placed across bothlamps 3 and 4. Since the lamps are negative resistance type devices,immediately upon lighting, most of the voltage will now be across lamp4, thereby causing it to start.

In the meantime, glow switch 5 remains fired since voltage is beingcontinually applied thereto. The impedance 9 should be of sufiicientvalue to keep the glow switch 5 fired during the operation of lamps 3and 4. To extinguish the lamps, switch S is opened. The voltage beingtaken off glow switch 5, the bimetallic contact 7 thereof is caused toagain close its contact with element 6- In FIG. 1, the lamps used areslim line fluorescent lamps which have opposite electrodes and employargon gas, a small portion of mercury, and is coated on its innersurface with fluorescent material. In this FIG. 1, as well as in FIGS. 2and 3, it will be noted that element 7 is bent to form a stop againstitself in the event glow switch 5 is overheated.

In one example, two 40 watt slim line fluorescent lamps rated at 600volts and 0.20 ampere were used. The lamp voltage was about 240 voltseach, totalling 480 volts. Thus, the reserve voltage was 120 volts. Thisreserve voltage acts as a ballast voltage and insures safe operation inthe event the line voltage should drop. It was found that in thisinvention, it was easy to start the lamps with the rated 600 voltsbecause of the short circuiting scheme of the glow switch used.

In FIG. 2, there is depicted a rapid start type (FLR) fluorescent lamp.Its operation is similar to that of the embodiment of FIG. 1, with theexception that instead of the voltage being applied to electrodes 3A, 3Band 4A, 4B, the voltages are taken from windings 1C, 1D and 1E andapplied to the filaments 3A, 3B, 4A, 4B of lamps 3 and 4. Otherwise, thestarting switch 5, is operated in the same manner as that for FIG. 1.

In FIG. 3, there is depicted an alternative circuit connection for arapid start type (FLR) fluorescent lamp. The only difierence betweenFIGS. 2 and 3, is the use in FIG. 3 of two filament heater windings 1Cand 1D and the direct connection of winding 4B to contact .7

and through capacitor-impedance combination 2-10. In

operation, when switch 5 is normally closed, lamp 4 is short circuitedthrough its filaments. This causes preheating of the lamp 4. When glowswitch 5 is caused to glow and after suflicient delay the contactbetween 6 and 7 is broken, and a higher starting voltage is developedacross lamp 4, thereby causing it to operate.

In a further embodiment, a thermal switch is substituted for the glowswitch 5. A metal filament coil may be'connected between the bimetallicelement 7 and element 8. The heat produced from the metal filament coildue to electrical current passed therethrough would cause the bimetallicelement 7 to move and to open the normally closed contact betweenelements 6 and 7.

It is to be understood that the foregoing is only illustrative of theprinciples'of this invention and that numerous other changes andmodifications would be obvious to one skilled in the art withoutdeparting from the spirit and scope of this invention.

What is claimedisz 1. A system for starting at least two gaseousdischarge devices which are connected in series circuit with each other,said series connected devices being connectable in parallel circuitacross a voltage source, said system comprising Y (1) impedance meansconnected in parallel circuit across one of said devices,

(2) starter switch means comprising a glow discharge tube having a firstelectrode, a second electrode, and a third electrode, said thirdelectrode being normally in electrical contact with said secondelectrode and moveable out of contact with said second electrode whensaid tube is in a glow discharge state,

(3) means for connecting said first electrode to said impedance means,

'(4) means for connecting said second electrode to both said impedancemeans and the interconnection between the series connected devices,

(5) means for connecting said third electrode and the non-seriesconnected terminal of the other of said devices, whereby said electricalcontact between said second and third electrodes short circuits saidother device thereby to cause said voltage source to start said onedevice, said impedance means being effective upon connecting of saidvoltage source to cause a glow discharge in said tube thereby to causeopening of said electrical contact between said second and thirdelectrodes and the placement of both said devices in series circuit witheach other and across said voltage source to cause said other device tobe started.

References Cited UNITED STATES PATENTS 2,423,031 6/1947 Kurtz et al.315189 X 2,542,149 2/1951 Lemaigre-Voreaux ZOO-113.5 2,866,133 12/1958Strange et a1. 315-98 X JAMES W. LAWRENCE, Primary Examiner. C. R.CAMPBELL, Assistant Examiner.

